1. Technical Field
The present invention relates to a method for manufacturing a printed circuit board.
2. Description of the Related Art
With package products becoming smaller and smaller, so also are circuit widths and via land sizes continuously decreasing, in order that circuit densities may be increased. In response to these trends, most board companies are working on developments for reducing the sizes of via holes and increasing the accuracy with which to align a via hole and a via land.
FIG. 1 to FIG. 7 are cross-sectional views illustrating a method of manufacturing a printed circuit board according to the related art, and FIG. 8 is a perspective view illustrating a via and circuit patterns according to the related art. Referring to FIGS. 1 to 8, a copper clad laminate 6 may first be prepared, in which a copper foil layer 4 is formed on either side of an insulation layer 2. Next, a via hole 8 may be formed using a drill bit or a laser. When the via hole 8 is formed, the surfaces of the insulation layer and the inner perimeter of the via hole 8 may be plated with copper to form a copper layer 10, by subjecting the copper clad laminate 6 to electroless plating and then electroplating. Next, the circuit patterns 14 and via land 12 may be formed by coating a plating resist, exposing, developing, etching, and stripping off the plating resist. Next, a solder resist 16 may be coated, with only the portions where pads are to be formed opened, by a series of exposing, developing, and drying. Finally, the process of manufacturing a printed circuit board can be completed by gold plating the bonding pads 18 or solder ball pads 20.
With this method, the via lands 12 may be formed during the circuit-forming process, to prevent-short circuiting in the electrical connections. In forming the circuit patterns, the size of the via lands 12 may be determined by the size of the via holes 8 and the accuracy with which it is possible to align the via hole 8 and via land 12.
However, in order to reduce the size of a via hole and increase the alignment accuracy, high investments may be needed, such as in high-precision drilling equipment and exposure equipment, and manufacturing costs may be increased due to decreased productivity.